{"id":144057,"date":"2024-11-01T03:49:44","date_gmt":"2024-10-31T19:49:44","guid":{"rendered":"https:\/\/server.hk\/cnblog\/144057\/"},"modified":"2024-11-01T03:49:45","modified_gmt":"2024-10-31T19:49:45","slug":"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e5%ae%8c%e6%95%b4%e6%80%a7%e7%b4%84%e6%9d%9f%e8%a9%b3%e8%a7%a3-sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ae%8c%e6%95%b4%e6%80%a7%e7%b4%84%e6%9d%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/144057\/","title":{"rendered":"SQL \u6578\u64da\u5eab\u4e2d\u7684\u5b8c\u6574\u6027\u7d04\u675f\u8a73\u89e3 (sql \u6578\u64da\u5eab\u5b8c\u6574\u6027\u7d04\u675f)"},"content":{"rendered":"

SQL \u6578\u64da\u5eab\u4e2d\u7684\u5b8c\u6574\u6027\u7d04\u675f\u8a73\u89e3<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u5b8c\u6574\u6027\u7d04\u675f\u662f\u78ba\u4fdd\u6578\u64da\u6e96\u78ba\u6027\u548c\u4e00\u81f4\u6027\u7684\u91cd\u8981\u6a5f\u5236\u3002\u9019\u4e9b\u7d04\u675f\u80fd\u5920\u9632\u6b62\u4e0d\u6b63\u78ba\u6216\u4e0d\u4e00\u81f4\u7684\u6578\u64da\u9032\u5165\u6578\u64da\u5eab\uff0c\u5f9e\u800c\u4fdd\u8b77\u6578\u64da\u7684\u5b8c\u6574\u6027\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e SQL \u6578\u64da\u5eab\u4e2d\u7684\u5404\u7a2e\u5b8c\u6574\u6027\u7d04\u675f\uff0c\u5305\u62ec\u4e3b\u9375\u7d04\u675f\u3001\u5916\u9375\u7d04\u675f\u3001\u552f\u4e00\u7d04\u675f\u3001\u6aa2\u67e5\u7d04\u675f\u548c\u9ed8\u8a8d\u7d04\u675f\u3002<\/p>\n

1. \u4e3b\u9375\u7d04\u675f (Primary Key Constraint)<\/h2>\n

\u4e3b\u9375\u7d04\u675f\u662f\u7528\u4f86\u552f\u4e00\u6a19\u8b58\u6578\u64da\u8868\u4e2d\u6bcf\u4e00\u884c\u7684\u5b57\u6bb5\u3002\u6bcf\u500b\u6578\u64da\u8868\u53ea\u80fd\u6709\u4e00\u500b\u4e3b\u9375\uff0c\u4e26\u4e14\u4e3b\u9375\u7684\u503c\u5fc5\u9808\u662f\u552f\u4e00\u7684\uff0c\u4e0d\u80fd\u70ba\u7a7a\u3002\u4e3b\u9375\u901a\u5e38\u7531\u4e00\u500b\u6216\u591a\u500b\u5217\u7d44\u6210\uff0c\u9019\u4e9b\u5217\u7684\u7d44\u5408\u5fc5\u9808\u80fd\u5920\u552f\u4e00\u6a19\u8b58\u6bcf\u4e00\u884c\u6578\u64da\u3002<\/p>\n

CREATE TABLE Users (\n    UserID INT PRIMARY KEY,\n    UserName VARCHAR(100),\n    Email VARCHAR(100)\n);<\/code><\/pre>\n
\u5728\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0cUserID \u5217\u88ab\u8a2d\u7f6e\u70ba\u4e3b\u9375\uff0c\u9019\u610f\u5473\u8457\u6bcf\u500b\u7528\u6236\u7684 UserID \u5fc5\u9808\u662f\u552f\u4e00\u7684\u3002<\/p>\n
2. \u5916\u9375\u7d04\u675f (Foreign Key Constraint)<\/h2>\n
\u5916\u9375\u7d04\u675f\u7528\u65bc\u5efa\u7acb\u5169\u500b\u8868\u4e4b\u9593\u7684\u95dc\u806f\u3002\u5b83\u78ba\u4fdd\u4e00\u500b\u8868\u4e2d\u7684\u67d0\u500b\u5b57\u6bb5\u7684\u503c\u5fc5\u9808\u5b58\u5728\u65bc\u53e6\u4e00\u500b\u8868\u7684\u4e3b\u9375\u4e2d\u3002\u9019\u6a23\u53ef\u4ee5\u7dad\u8b77\u6578\u64da\u7684\u53c3\u8003\u5b8c\u6574\u6027\uff0c\u9632\u6b62\u51fa\u73fe\u5b64\u7acb\u7684\u6578\u64da\u3002<\/p>\n
CREATE TABLE Orders (\n    OrderID INT PRIMARY KEY,\n    UserID INT,\n    FOREIGN KEY (UserID) REFERENCES Users(UserID)\n);<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cOrders \u8868\u4e2d\u7684 UserID \u5217\u662f\u5916\u9375\uff0c\u6307\u5411 Users \u8868\u4e2d\u7684 UserID \u5217\u3002\u9019\u610f\u5473\u8457\u6bcf\u500b\u8a02\u55ae\u90fd\u5fc5\u9808\u8207\u4e00\u500b\u6709\u6548\u7684\u7528\u6236\u76f8\u95dc\u806f\u3002<\/p>\n
3. \u552f\u4e00\u7d04\u675f (Unique Constraint)<\/h2>\n
\u552f\u4e00\u7d04\u675f\u78ba\u4fdd\u67d0\u4e00\u5217\u6216\u67d0\u5e7e\u5217\u7684\u503c\u5728\u6574\u500b\u8868\u4e2d\u662f\u552f\u4e00\u7684\u3002\u8207\u4e3b\u9375\u4e0d\u540c\u7684\u662f\uff0c\u552f\u4e00\u7d04\u675f\u5141\u8a31\u5217\u4e2d\u6709\u7a7a\u503c\uff0c\u4f46\u6bcf\u500b\u975e\u7a7a\u503c\u5fc5\u9808\u662f\u552f\u4e00\u7684\u3002<\/p>\n
CREATE TABLE Products (\n    ProductID INT PRIMARY KEY,\n    ProductName VARCHAR(100) UNIQUE\n);<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cProductName \u5217\u88ab\u8a2d\u7f6e\u70ba\u552f\u4e00\u7d04\u675f\uff0c\u9019\u610f\u5473\u8457\u6bcf\u500b\u7522\u54c1\u7684\u540d\u7a31\u5fc5\u9808\u662f\u7368\u4e00\u7121\u4e8c\u7684\u3002<\/p>\n
4. \u6aa2\u67e5\u7d04\u675f (Check Constraint)<\/h2>\n
\u6aa2\u67e5\u7d04\u675f\u7528\u65bc\u9650\u5236\u5217\u4e2d\u7684\u503c\uff0c\u78ba\u4fdd\u5b83\u5011\u7b26\u5408\u7279\u5b9a\u7684\u689d\u4ef6\u3002\u9019\u53ef\u4ee5\u7528\u4f86\u5f37\u5236\u57f7\u884c\u696d\u52d9\u898f\u5247\u3002<\/p>\n
CREATE TABLE Employees (\n    EmployeeID INT PRIMARY KEY,\n    Age INT CHECK (Age >= 18)\n);<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cAge \u5217\u7684\u6aa2\u67e5\u7d04\u675f\u78ba\u4fdd\u6240\u6709\u54e1\u5de5\u7684\u5e74\u9f61\u5fc5\u9808\u5927\u65bc\u6216\u7b49\u65bc 18 \u6b72\u3002<\/p>\n
5. \u9ed8\u8a8d\u7d04\u675f (Default Constraint)<\/h2>\n
\u9ed8\u8a8d\u7d04\u675f\u7528\u65bc\u70ba\u5217\u6307\u5b9a\u4e00\u500b\u9ed8\u8a8d\u503c\uff0c\u7576\u63d2\u5165\u6578\u64da\u6642\u5982\u679c\u6c92\u6709\u63d0\u4f9b\u8a72\u5217\u7684\u503c\uff0c\u5247\u6703\u4f7f\u7528\u9019\u500b\u9ed8\u8a8d\u503c\u3002<\/p>\n
CREATE TABLE Products (\n    ProductID INT PRIMARY KEY,\n    Stock INT DEFAULT 0\n);<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cStock \u5217\u7684\u9ed8\u8a8d\u503c\u8a2d\u7f6e\u70ba 0\uff0c\u9019\u610f\u5473\u8457\u5982\u679c\u5728\u63d2\u5165\u7522\u54c1\u6642\u672a\u6307\u5b9a\u5eab\u5b58\u6578\u91cf\uff0c\u5247\u5eab\u5b58\u5c07\u81ea\u52d5\u8a2d\u7f6e\u70ba 0\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5b8c\u6574\u6027\u7d04\u675f\u5728 SQL \u6578\u64da\u5eab\u4e2d\u626e\u6f14\u8457\u81f3\u95dc\u91cd\u8981\u7684\u89d2\u8272\uff0c\u5e6b\u52a9\u78ba\u4fdd\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u4e00\u81f4\u6027\u3002\u901a\u904e\u4f7f\u7528\u4e3b\u9375\u3001\u5916\u9375\u3001\u552f\u4e00\u3001\u6aa2\u67e5\u548c\u9ed8\u8a8d\u7d04\u675f\uff0c\u6578\u64da\u5eab\u7ba1\u7406\u8005\u53ef\u4ee5\u6709\u6548\u5730\u7dad\u8b77\u6578\u64da\u7684\u5b8c\u6574\u6027\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u7ba1\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\u3002\u82e5\u60a8\u5c0d\u65bc \u9999\u6e2f VPS<\/a> \u6216\u5176\u4ed6\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u611f\u8208\u8da3\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u6df1\u5165\u63a2\u8a0eSQL\u6578\u64da\u5eab\u4e2d\u7684\u5b8c\u6574\u6027\u7d04\u675f\uff0c\u4e86\u89e3\u5176\u985e\u578b\u3001\u529f\u80fd\u53ca\u5982\u4f55\u78ba\u4fdd\u6578\u64da\u7684\u6e96\u78ba\u6027\u8207\u4e00\u81f4\u6027\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-144057","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144057","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=144057"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144057\/revisions"}],"predecessor-version":[{"id":144058,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/144057\/revisions\/144058"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=144057"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=144057"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=144057"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}